Just a few unreliable thoughts . . .
As Bosco' says, I'd try to avoid the triptan. It sounds like you are doing that the best you can. Many people find that ginger helps a lot with shadows. Ginger tea (store-bought made from real ginger, or made yourself by peeling and boiling some ginger (look up specifics on google)); ginger candy (Ginger People or crystallized ginger); non-alcoholic ginger beer. Excedrin helps some with shadows.
Some people find that frequent use of caffeine reduces its effectiveness. You gotta do what you gotta do, so this is again just a thought for you to consider. Basically, try not to drink it when you don't need it.
You might try some Benadryl, since sometimes persistent CH stuff results from allergies. I think Batch would suggest trying Quercetin first, because it's less drowsy-making. He suggests 3 grams/day, but you might start less than that (or not). Some people stick with the Benadryl (roughly 25 mg four times a day, as tolerated).
I'm not sure that O2 is good for shadows. I just don't know. Haven't read of many people using it for that, but if it has worked for you, one possible reason it might be less effective now is that O2 is (for many people) less effective when the tank gets low on O2 -- maybe 1/3 full, or less.